Most types of protective helmets worn by workers to protect them from falling objects have a suspension system. The suspension system or headgear support, along with the helmet shell, act to absorb the shock of a falling object striking the top of the worker's head. The suspension system also serves as a support that holds the helmet or faceshield on the worker's head.
The suspension is often a web-like support system comprising two or more strips of material that are arranged to cross each other. The ends of the strips are, for example, attached at four or more points around the circumference of the helmet. A headband is then typically attached to the four or more points of the suspension to permit the helmet to be worn by the worker. To securely position the helmet on the worker's head, it is essential that the circumference of the headband be adjustable to fit the appropriate head size. An adjustable napestrap is often attached at one end of the headband to achieve these results. Such a suspension system is available from Mine Safety Appliances Company of Pittsburgh, Pa. under the trademark STAZ-ON®.
U.S. Pat. No. 3,500,474, the disclosure of which is incorporated herein by reference, discloses a headband wherein the napestrap position of the headband is manually adjusted by the wearer to fit the appropriate head size. The two ends of the headband are connected and held in place by a slot-and-projection arrangement. One end of the headband is formed with parallel rows of projections or flanges. The other end of the headband is formed with parallel rows of slots. The size of the headband can be adjusted by inserting the projections of one end of the strap into the slots formed in the other end of the strap at the desired length. Although this type of headband is relatively simple in design and manufacture (in part because separate mechanical fasteners or adjustment mechanisms are generally not required), users of such bands often have difficulty adjusting the band size while wearing the suspension. This inconvenience often results in the use of a different, more expensive type of suspension, such as a ratchet-type suspension system as, for example, described in U.S. Pat. No. 4,942,628.
U.S. Pat. No. 5,896,586, the disclosure of which is incorporated herein by reference, discloses a headband that is relatively simple and inexpensive to manufacture, while providing a fastening mechanism that is relatively easy to adjust. The headband can be fabricated from an integral or monolithic piece of polymeric material. That headband includes a first end and a second end which overlap. The first end includes a plurality of longitudinally spaced attachment members (for example, depressions, recesses or slots). The second end includes a resilient fastener having an opening or a channel to slidably receive the first end in overlapping engagement with the second end. The fastener also includes a fastener surface having at least one cooperating attachment member to cooperate with the attachment members of the first end of the band. The fastener surface is resiliently bowable in a direction away from the first end upon application of a compressive force to the fastener. Upon application of such compressive force, the attachment member of the first end of the band and the cooperating attachment member of the fastener disconnect so that the first end can be slid relative to the fastener (and thereby the second end). Unfortunately, it can be difficult to operate the bowable fastening mechanism of U.S. Pat. No. 5,896,586 with only one hand.
U.S. Pat. No. 6,341,382 also discloses a one-piece adjustable headband which is constructed of lightweight material such as a plastic. The strap is constructed with an integral adjustment or fastening mechanism to adjust the fit of the strap around the head of wearer, purportedly using a single hand. The headband includes a first end, a second end, an interior surface, and an exterior surface. A plurality of ratchet teeth extend from the exterior surface of the headband adjacent the first end thereof. Each of the ratchet teeth has a tapered surface and a locking surface. A clasp is resiliently connected to the exterior surface of the headband adjacent the second end thereof. The clasp includes a pawl which is biased in a locking position wherein the pawl is engageable with the locking surface of one of the ratchet teeth to hold the headband in a selected loop configuration. The clasp is movable to a release position upon application of a force generally normal to the plane of the headband whereby the pawl is moved away from the ratchet teeth to permit the loop configuration of the headband to be increased in size.
Although a number of fastening or adjusting mechanisms have been developed for headbands or head straps for use in headgear, and especially in personal protective equipment such as protective helmets, faceshields and welding shields having a headgear support, it remains desirable to develop improved headbands and adjusting mechanism for use therein, particularly ones which can be adjusted using only one hand, and preferably which can also be adjusted while a user is wearing the protective headgear support.